Key points of the study: -Intraoperative radiotherapy is an alternative to postoperative radiotherapy for patients with early-stage breast cancer and has certain advantages, but there is no randomized controlled study to evaluate how well this treatment can control local recurrence; -Intraoperative radiotherapy is less damaging to the skin and contributes to the success of postoperative prosthesis implantation. Although the IBTR rate in the intraoperative radiotherapy group was within the predefined range of the investigators, it was still significantly higher than the IBTR rate in the external radiotherapy group, but the two treatment modalities did not have a significant effect on the overall survival of patients with early-stage breast cancer (small tumors). Intraoperative radiotherapy with electrons is an alternative to conventional postoperative whole-breast radiotherapy, which is administered in a single session at the same therapeutic dose. However, the ability to control local recurrence with this treatment modality needs to be verified in further randomized controlled studies. Therefore, Umberto Veronesi et al. from the European Agency for Oncology in Italy designed the relevant study and published their findings in the November online issue of Lancet Oncol. The study was conducted at the European Institute for Oncology Research in Milan, Italy. Subjects included were women aged 48 to 75 years with early-stage breast cancer, with a maximum tumor diameter of 2.5 cm, and who were suitable for breast-conserving surgery, and who met the above enrollment criteria were randomized in a 1:1 ratio into 2 groups, with randomized grouping using a randomized permutation method, and patients were stratified according to tumor size (<1.0 cm vs 1.0C1.4 cm vs ≥1.5 cm). Stratification was performed. One group of patients received total external breast radiotherapy and the other group underwent electron radiation therapy during surgery. The study coordinators, specialists, and patients were informed of the specific treatment regimen they received. Patients in the intraoperative radiotherapy group received a single intraoperative dose of 21 Gy of radiation therapy to the tumor site. Patients in the external radiotherapy group received a total dose of 50 Gy in 25 sessions of 2 Gy each, followed by a total dose of 10 Gy in 5 sessions after completion. The study was an equivalence study, and the pre-determined equivalence range was 7.4% local recurrence rate for patients in the intraoperative radiotherapy group. The primary endpoint event for this study was the ipsilateral breast tumor recurrence (IBTR) status, and the secondary endpoint was overall survival. The investigators used an intention-to-treat analysis to perform the primary analysis of the study results. The study was registered with ClinicalTrials.gov under registration number NCT01849133. Between November 20, 2000, and December 27, 2007, the investigators randomized a total of 1,305 patients, 654 in the external radiation group and 651 in the intraoperative radiotherapy group. After a median follow-up period of 5.8 years, 35 patients in the intraoperative radiotherapy group developed IBTR compared with 4 in the external radiotherapy group, with a statistically significant difference between the two groups. The 5-year IBTR incidence was 4.4% in the intraoperative radiotherapy group and 0.4% in the external radiotherapy group, with an HR of 9.3%, again with a statistically significant difference. The 5-year overall survival rates were 96.8% and 96.9% in the intraoperative and external radiotherapy groups, respectively. Of the patients whose data were available for analysis (464 in the intraoperative radiotherapy group and 412 in the external radiotherapy group), the investigators noted a statistically significant reduction in the number of female patients in the intraoperative radiotherapy group who had adverse skin reactions. The results of this study indicated that although the IBTR rate in the intraoperative radiotherapy group was within the investigators' pre-determined range, it was still significantly higher than the IBTR rate in the external radiotherapy group, but there was no significant difference in overall survival between the two groups. The investigators noted the need to further improve patient inclusion, which would reduce the IBTR rate in the intraoperative radiotherapy group. Address correspondence to: http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(13)70497-2/fulltext (Reprinted from Clove)